Method

1. Heat a large saucepan of lightly salted water until boiling for the pasta.

2. Meanwhile, heat half the butter with the oil in a frying pan until no longer foaming and feeling hot.

3. Add the liver and fry for 1-2 minutes on each side until well browned and just firm when pressed with the back of a fork.

4. Season in the pan, then remove to a warmed plate and keep warm.

5. Add the port or Madeira to the pan, bring to the boil and allow to bubble until reduced by half.

6. Add the vinegar and cook for a few seconds.

7. Pour in the stock and bring to the boil, stirring. Continue to boil until reduced by half.

8. Meanwhile, add the pasta to the pan of boiling water and cook for 2-3 minutes for fresh pasta or according to the packet instructions for dried pasta until just tender.

9. Drain, then toss with the remaining butter and the fresh or dried sage.

10. Season the pasta well and divide between two warmed serving plates.

11. Lay the liver over the top (you may want to slice this first).

12. Whisk the crème fraîche into the sauce in the pan, if using. Check the seasoning and spoon over the liver. Serve immediately